Micronutrient supplementation has limited effects on intestinal infectious disease and mortality in a Zambian population of mixed HIV status: a cluster randomized trial.

BACKGROUND: Diarrheal disease remains a major contributor to morbidity and mortality in Africa, but host defense against intestinal infection is poorly understood and may depend on nutritional status. OBJECTIVE: To test the hypothesis that defense against intestinal infection depends on micronutrient status, we undertook a randomized controlled trial of multiple micronutrient supplementation in a population where there is borderline micronutrient deficiency. DESIGN: All consenting adults (> or =18 y) living in a carefully defined sector of Misisi, Lusaka, Zambia, were included in a cluster-randomized (by household), double-blind, placebo-controlled trial with a midpoint crossover. There were no exclusion criteria. Participants were given a daily tablet containing 15 micronutrients at just above the recommended nutrient intake or placebo. The primary endpoint was the incidence of diarrhea; secondary endpoints were severe episodes of diarrhea, respiratory infection, nutritional status, CD4 count, and mortality. RESULTS: Five hundred participants were recruited and followed up for 3.3 y (10,846 person-months). The primary endpoint, incidence of diarrhea (1.4 episodes/y per person), did not differ with treatment allocation. However, severe episodes of diarrhea were reduced in the supplementation group (odds ratio: 0.50; 95% CI: 0.26, 0.92; P = 0.017). Mortality was reduced in HIV-positive participants from 12 with placebo to 4 with supplementation (P = 0.029 by log-rank test), but this was not due to changes in CD4 count or nutritional status. CONCLUSION: Micronutrient supplementation with this formulation resulted in only modest reductions in severe diarrhea and reduced mortality in HIV-positive participants. The trial was registered as ISRCTN31173864

Do input subsidy programs "crowd in" or "crowd out" commercial market development? Modeling fertilizer demand in a two-channel marketing system

Many governments in developing countries distribute fertilizer at subsidized prices in an effort to stimulate small farmers' agricultural productivity and food security. Prior fertilizer demand studies have largely failed to account for the effects of government programs on farmers' commercial purchases. Using a double hurdle model and nationally representative rural household panel data in Zambia, we distinguish between these sources and measure the contemporaneous "crowding in" and "crowding out" effects of government input programs on commercial fertilizer sales. Where the private sector is relatively active and average wealth is higher (areas seemingly more likely to be targeted by government programs), results indicate that subsidies have substantially crowded out the private sector, in some cases to the point that such programs could actually lower overall fertilizer use. On the other hand, in poorer areas where the private sector is relatively inactive, subsidies help to generate demand and crowd in private sector retailers. Empirical studies explicitly modeling farmers' fertilizer purchase behavior within a dual marketing framework can provide important insights for agricultural policy discussions in developing countries. Copyright (c) 2009 International Association of Agricultural Economists.